I've bitten the bullet and have begun to author parts for LDraw. I've started by looking at stickers, as they seem to be an easier entry point than other physical parts. One sticker I'm currently working on is a train logo from the set 7939-1 (Cargo Train).

For the purpose of this conversation, this sticker is roughly 80 LDUs wide. There is a second sticker with the same symbol / yellow background which is roughly 40 LDUs wide.

I can think of a couple of options for creating the 80 LDU and 40 LDU stickers;
1) duplicate the shapes related to the logo in their entirety from the 80 LDU sticker to the 40 LDU sticker
2) create a sub-part (?) containing the logo within a rectangular area. Define an 80 LDU and 40 LDU sticker whose content would then be an appropriately sized "hollow" rectangle plus the sub-part

I am looking for advice as to which of these options would be preferred/recommended/expected/required. Or, indeed, if there is another option to which I should comply.

Bonus question for 10 points. The sticker background is yellow. If I use the create a sub-part option, would there be any value to create the sub-part with a colour of "16" and then in the containing part, specify the appropriate colour value for yellow? My premise is that by having the sub-part with a colour of "16", it improves the potential for re-use in other parts, should the same size train logo be used in other sets.